CSF-1 promoter/first intron–driven β-galactosidase (TgZ) expression in hematopoietic tissues.

Stained with H&E (A, C, E, G), X-gal (A-I; some positive cells indicated by black arrows), and TRAP (I; some TRAP-positive cells indicated by red arrows). (A, B) Spleen, indicating staining of cells in the marginal zone (MZ), less intensely in the red pulp (RP), and their exclusion from the white pulp (WP). (C, D) Lymph node, showing staining of the outer cortex (OC) and the region (*) between 2 germinal centers (GC). (E, F) Thymus, revealing the presence of scattered cells in the cortex. (G-I) Bone marrow, showing β-galactosidase–expressing cells and TRAP-positive cells lining the surfaces of the bony trabeculae (T) in regions in which bone marrow fibroblasts, osteoblasts, and osteoclasts reside. TRAP-positive cells are also shown in the primary center of ossification (CO). Nuclear staining of β-galactosidase is often accompanied by some cytoplasmic staining, due to incomplete transfer of the enzyme to the nucleus. Bars: 50 mm.